1. Technical Field
The present invention relates to a seal nut. In particular, the present invention relates to a seal nut for blocking fluid flow through an opening extending from a pressure chamber in a fluid power assist steering gear.
2. Description of the Prior Art
Fluid power assist steering gears for vehicles are known. One such steering gear is disclosed in U.S. Pat. No. 4,773,303 and includes a piston which moves axially in a fluid pressure cheer. The piston is connected through a pitman arm with the steerable wheels of the vehicle. The steerable wheels, at the end of their range of movement, engage steering stops on the vehicle.
It is important to relieve fluid pressure in the chamber prior to engagement of the steerable wheels with the steering stops. Relieving the pressure protects the power steering pump and other parts of the steering gear and steering linkage from damage.
The steering gear disclosed in U.S. Pat. No. 4,773,303 includes poppet valves on the piston which are operative to relieve the fluid pressure Just prior to the steerable wheels reaching their limit of movement. An opening extends through a wall of a housing of the power steering gear, between the pressure chamber and an outer surface of the housing. An adjusting screw is threaded in the opening and has a portion projecting into the pressure chamber. The adjusting screw is movable axially relative to the housing to adjust the position of the poppet valves. A jam nut is threaded onto a portion of the adjusting screw which projects outwardly from the outer surface of the housing. The jam nut engages the housing outer surface to prevent the adjusting screw from moving from the adjusted position.
The inner end of the adjusting screw, and the inner end of the opening in the housing wall, are exposed to the pressure of the power steering fluid in the pressure chamber. This pressure can be as much as 5,000 psi. Power steering fluid under this pressure may tend to flow outwardly through the opening to the outer surface of the power steering gear. It is desirable to block fluid flow through the opening in the housing wall to prevent loss of fluid from the pressure cheer in the power steering gear.